Subs' Hull Problems Resurfacing

Problems With Submarines' Steel Hulls In '60s Resurface In '90s

Difficulty With Stronger Steels Continues

C When the atomic submarine USS Thresher went down on April 10, 1963, crushed by the weight of the sea, the Navy lost more than a boat and 129 men.

The Navy lost its nerve.

It backed away from an ambitious research program that had developed stronger and lighter hull steels to give submarines the ability to dive deeper and carry more equipment.

Now, the Navy is paying for its timidity. The Seawolf, the Navy's most advanced submarine ever and the first boat since the Thresher to have a different kind of hull steel, is about to be torn apart.

About 15 percent of the first Seawolf hull had been built at the Electric Boat shipyard in Groton before microscopic cracks, indicating brittleness, were discovered in welds this summer.

Nearly two years of construction work will have to be scrapped, according to consultants who were called to Washington 1 1/2 weeks ago to confer with the Navy on the problem.

The cost may reach hundreds of millions of dollars.

As Navy officers pointed out to the consultants, no lives have been lost, but the situation is serious. At stake are the future of the Seawolf program and the survival of Electric Boat, Connecticut's second-largest private employer.

The hull of the Seawolf, the submarine that is supposed to lead the Navy into the 21st century, is being built with steel and welding techniques developed in the 1950s and 1960s.

The Thresher, built in the late 1950s at a government shipyard in Portsmouth, N.H., never completed its sea trials.

When it was lost in 8,400 feet of water 220 miles east of Cape Cod, the submarine was testing its deep diving capability. The wreckage was located, but the cause of the accident was never pinned down.

A Navy inquiry advanced the theory that a pipe failure in the Thresher's seawater cooling system probably triggered a series of events that left the submarine unable to surface.

But testimony at congressional hearings in 1963 and 1964 on the

Thresher tragedy raised serious questions about the quality of the Navy's submarine construction program and its ability to work with the then-new, high-strength steels.

"Drastic action must be taken to upgrade our design activities and shipyards so that design, fabrication methods and inspection techniques are commensurate with the high-performance materials being used," testified Hyman G. Rickover, then a vice admiral and assistant chief of the Navy's Bureau of Ships in charge of nuclear propulsion.

Rickover, an engineer who was known as the father of the nuclear Navy, did not like the high-strength steels developed through the Navy's research and development program.

The Thresher's hull was made of one of those steels, called HY-80. It was first approved for submarine construction in 1955. The "HY" stands for high-yield strength, and the "80" means that the steel is designed to withstand 80,000 pounds of pressure per square inch before permanently deforming.

Rickover noted that the Navy and its shipbuilders had encountered weld-cracking problems while working with HY-80 and questioned the soundness of the Thresher's hull.

"Acceptance of a structural hull material which is prone to cracking, and which frequently must be inspected and repaired, as the price of being able to go deeper, is questionable," he testified.

Another Navy officer, Rear Adm. C. A. Curtze, a deputy chief with the Bureau of Ships, was more comfortable with the steel. He testified that problems welding HY-80 had been largely overcome.

But Curtze also said the maximum depths of deep-diving submarines had been restricted pending the outcome of all reviews of the Thresher accident. And he noted that the Navy had launched a new submarine safety program.

"On hindsight," Curtze testified, "with respect to submarine design, we moved too fast and too far. ... Submarine safety did not keep pace." The loss of the Thresher was the worst peacetime naval disaster in U.S. history.

Then, just five years later, in May 1968, the Navy lost another submarine, the USS Scorpion, which sank in the Atlantic approximately 400 miles southwest of the Azores with 99 crewmen aboard. What happened is a mystery. The Navy has never released a report on the accident. The Scorpion, built by Electric Boat in the late 1950s, was commissioned in 1960.

Through the 1960s, the 1970s and the 1980s, the Navy stuck with HY-80 for building submarine hulls. It continued to have periodic cracking problems. In 1979, Navy inspectors found flaws in several submarines that led to an estimated $100 million in ripout and repair work.

Meanwhile, other countries -- most notably the Soviet Union and Japan -- forged ahead of the United States in the use of stronger and lighter hull steels. The Japanese have worked with steels first developed by the United States, and the Soviets have used titanium in some of their submarines.

While the United States has lost two submarines since World War II, the Soviets are believed to have lost at least five.